Elucidating the Optical Properties of Novel Heterolayered Materials Based on MoTe₂–InN for Photovoltaic Applications

Abstract

Efficient excitonic solar cells preferably require materials with an optical gap in the near-infrared region and high absorption coefficients. Additionally, it is well-known that heterostructures open the possibility of tailoring device properties by taking advantage of the characteristics of individual materials, so that new practical applications can arise. Regarding these ingredients, we propose that the recent synthesized monolayer MoTe 2 and the InN compound seem to favorably fit into this category. We carry out ab initio density functional theory calculations to study the electronic and optical properties of heterostructures based on MoTe 2 and InN monolayers. Our results indicate that one of the most stable heterostructures presents type-II band alignments and photoexcited states in the energy range of 1.1−1.3 eV, where power conversion efficiency reaches its maximum. We also propose a prototypical device based on these materials and study their potential as excitonic solar cells. In doing so, we show that heterostructures based on MoTe 2 −InN are able to combine the nearinfrared absorption of MoTe 2 together with the low refractive index and high absorbance of InN to give rise to improved optical properties such as the formation of photoexcited states with lower binding energies, when compared with the individual monolayers, long exciton lifetimes in the nanosecond scale, as well as high power density ratios. These overall results point toward the potential of MoTe 2 −InN heterostructures for photovoltaic applications.

Strain tuning of excitons in monolayer WSe2

“…Therefore, the optical and electrical properties of 1Ls may be strongly influenced by the exciton-and carrierphonon scattering between valleys at room and elevated temperatures 19,[21][22][23] . It has been proposed that tensile strain can alter the energy separation between those two states associated with the direct and indirect gaps, affecting the scattering rates [24][25][26][27] . Consequently, we expect that the altered energy separation under strain may lead to observable fingerprints in the optical spectra of the material.…”

“…We propose that origin of the strong strain dependence of γ KK−KQ arises from the near degeneracy of the KK and KQ excitons, so that slight shifts in the relative positions of the valleys can have a dramatic impact on scattering rates. In fact, the energy separation between the KQ and KK states, E KQ−KK , is expected to increase due to weaker (stronger) coupling between the orbitals contributing to the K (Q) point of CB under tensile strain [24][25][26][27]39 . Such a shift in the relative energies of the states can lead to a rapid decrease in the scattering rate due to a reduction in the density of available final states in the scattering process 24 .…”

Rh-doped MoSe2 as a toxic gas scavenger: a first-principles study

“…In the meanwhile, group III-V nitrides, particularly AlN and InN, 16,17 have been regarded as promising structures for gas sensing, 18,19 and the experimental breakthrough in the synthesis of InN 20 makes it possible to be used as a substitute for graphene with inherent bandgap characteristics. 21 Very recently, 2D transition metal dichalcogenides (TMDs), especially MoS 2 monolayers, [22][23][24] have attracted much attention as alternative materials to conventional metal oxides for chemical sensing devices. Moreover, surface doping with transition metal (TM) atoms has been demonstrated to provide a monolayer with enhanced adsorption and sensing performance for gas molecules [25][26][27][28] due to the improved chemical activity and electron mobility induced by the TM dopant, 29 opening up a novel insight into the sensor family.…”

Structural, electronic and optical properties of graphene-like nano-layers MoX2(X:S,Se,Te): DFT study

“…Recently, some applications have been reported for MoS 2 compositions like the heterolayer structure [25,26], FETs and memory devices with two-structure MoS 2 -Gr [27,28]; photodetector devices include p-n junction [29] and MoS 2 -WS 2 [30], in photovoltaic devices from Au-MoS 2 -Au [31] and other heterostructures [32][33][34]. The MoTe 2 compositions have many applications, especially in optical devices, which one of them is in the novel heterolayer materials based on MoTe 2 -In [35]. Generally, the results indicate that quantum confinement of carriers within monolayers can be exploited in conjunction with chemical composition to tune the optoelectronic properties of layered transition metal dichalcogenides at the nanoscale [36].…”